We consider a generalized derivative nonlinear Schrödinger equation. In [13, Theorem 2], the author showed that there exists a modied wave operator with suitable regular small asymptotic states given at innity. In this paper, we prove existence of wave operator under an explicit smallness of the given asymptotic states. Our method bases on studying the associated system used in [17]. Moreover, we show that if initial data is small in H 2 (R) then the associated solution scatters up to Gauge transformation in sense of Theorem 1.3.